The present invention relates to a safety interlock device for an electrically driven household mixing apparatus. More particularly, it relates to a safety interlock device for a household mixing apparatus which has a housing with an electric motor, a container having a body portion and a removable cover, and a heating device for heating the container.
Mixing apparatuses for household use are known in the art. Such mixing apparatuses have a holding lever turnably mounted on a housing of a motor or on a support. The lever has a free end portion adapted to engage the cover of the container. The free end portion of the holding lever is held on the cover or holds the latter closed. When the lever is turned off and its holding action is terminated, the drive motor will be switched off. In this construction, the holding lever is turnably mounted in the support and is releasably pressed against the cover by means of a tightening bolt provided on the end of the holding lever. Turning of the entire lever actuates a switch which switches off the drive motor. In this case there is a substantial disadvantage that closing of the container involves the tightening of this bolt as a prerequisite (interlock) for operation of the mixer, and thereafter, during opening of the container the lever must be released by untightening of the bolt. Another disadvantage of the above construction is that the drive motor can be again switched on when the cover is not on and the lever approaches the container, inasmuch as the switch of the drive motor is operated solely by turning of the lever. When the cover is open, the instrumentalities are accessible which is, of course dangerous.
Other mixing apparatuses have been proposed wherein a container is closed by a cover provided with raised outer ribs and has a lever axially movable against the action of a spring. The lever extends over the ribs of the cover and urges the latter towards the container. This construction possesses certain disadvantages because the turnable lever is mounted on the container and can operate a safety switch only with substantial difficulties. Furthermore, it has also a great disadvantage in that the turnable lever must be closed exactly in its end position, inasmuch as otherwise it will be withdrawn by the action of the spring and by a resulting force produced on the ribs. It is also necessary to produce the cover of a material which can assure engagement of the end portion of the turntable lever after repeated applications.